Researchers are using wheat and canola straw to remove arsenic from water
By Diego Flammini
Scientists in Saskatchewan are using ag waste to make clean water.
Khaled Benis, a Vanier Scholar and Ph.D. candidate at the University of Saskatchewan’s college of engineering, and his colleagues, have identified how to transform wheat and canola straw into a filter capable of absorbing arsenic from water.
Canada produces about 47 million tonnes of ag residue per year.
“We make the (crop residue) similar to activated carbon or ion exchange resin that can be used as alternatives to expensive materials. Crop residue is available everywhere and is a sustainable material.” Benis told Farms.com. “We collect the residues and perform physical or chemical treatments to activate the potential to absorb the arsenic.”
Over 200 million people in more than 70 countries, including Canada, are drinking water with high levels of arsenic, which can cause cancer, heart disease and respiratory issues.
Health Canada’s maximum acceptable concentration of arsenic in drinking water is 10 micrograms per litre.
For context, areas in Bangladesh and India have reported 4,730 and 3,700 micrograms of arsenic per litre of water, respectively, a 2018 study says.
Benis and his team tested multiple water samples. Some were from Saskatchewan taps, some samples were manipulated in the lab and some came from a mining operation.
The team started with a sample containing 1,000 micrograms of arsenic.
The ag residue produced impressive results.
“The crop residue was able to reduce the concentration to below 10 micrograms per litre,” Benis said.
The researchers use the Canadian Light Source (CLS), which is the brightest light in Canada and even brighter than the sun, to conduct their experiments.
CLS allows the scientists to identify how the crop residue changes after treatment, Benis said.
“We can see how the chemical or physical treatments change the structure of the residue, or how the arsenic goes through the residue and attach to the surface,” he said.
This kind of water filtration can be used and to fit different applications.
From a rural community with a well to a large municipality with a water treatment facility, the same principles apply, Benis said.
“You can take agricultural residue from the (local area) and have it treated to act as a filter,” he said. “We want to make it possible for others to use these methods to clean their water.”
The next step in the research is to identify is the residue can be manipulated to absorb other pollutants.
Multiple health and environmental organizations have identified multiple “contaminants of emerging concern.” These can include pharmaceuticals or personal care products.
“This is what we’re working on for the next two years,” Benis said. “We’ll hope to have published results about the different pollutants.”